Generally, the feeding unit comprises a dispenser for feeding a given amount of powdered material onto the lifting platform and a distributor for distributing the powdered material on the lifting platform itself.
The dispenser normally comprises a paddle wheel or a wheel with dispensing chamber configured for transferring the powdered material from a containment tank to the lifting platform.
The distributor normally comprises an elongated plate, which is made to advance in a transverse direction to distribute the powdered material over the lifting platform.
Known laser 3D printers of the type described above present some drawbacks mainly resulting from the fact that, to guarantee proper and precise dispensing of the powdered material onto the lifting platform, the paddle wheel or the wheel with dispensing chamber must present relatively high processing tolerances and is hence relatively complex and costly.